Histología y morfometría del ojo del pez dulceacuícola Paracheirodon axelrodi (Characiformes: Characidae)

Abstract

Histology and morphometry of the eye in the freshwater Paracheirodon axelrodi (Characiformes: Characidae). The visual system of Teleost fishes has a wide range of adaptations. The eye has suffered modifications, mainly towards better sensitivity and visual resolution according to specific environmental conditions. In that way, this organ is so important for survival. In spite of being the most commercialized Orinoquía species, and one of the most important ornamental fish worldwide, there are almost no studies on the communication systems of P. axelrodi (including vision). We studied the eye in ten individuals of P. axelrodi, with a mean total length of 2.7 cm (SD= 0.2, n= 20). We measured eye relative size (TRO) after sacrifice. Heads were processed for hematoxylin-eosin, and 8 µm thick sections were obtained. Images were digitalized for histological identification and morphometrics. The relation between TRO and body length was 9.8% (SD= 1.1, n= 20); lens was spherical with a relative size of 64.3% (SD= 4.9, n= 20). Rete mirabilis choroid was composed mainly by capillaries, while sclera was composed of cartilaginous tissue. Retina with eight layers and two membranes. An areae centrales was observed in the posterior retina. Iris covered by a simple cubic epithelium. Cornea of endotelial tissue with two membranes. Pupil almost circular, with a naso-caudal elongation. Measures of retina thickness were as follows:

Estudio Histológico del Tracto Digestivo del Neón Cardenal Paracheirodon axelrodi (Characidae)

“…Se trabajó con 15 ejemplares de P. axelrodi de longitud total 2,7+/-0,19 cm. Se sacrificaron con MS-222 (0,5 g/L) (Tovar et al, 2009). Se fijaron en formaldehído al 4 %, (pH 7,2-7,3), durante cinco días a 4 °C (Jaramillo et al, 2009).…”

Topological and histological description of preoptic area and hypothalamus in cardinal tetra Paracheirodon axelrodi (Characiformes: Characidae)

“…Therefore, several studies have focused on understanding its basic biology, as an imperative step to find sustainable exploitation strategies (Burton et al, 1998;Walker, 2004;Anjos, Anjos, 2006;Oliveira et al, 2008;Tovar et al, 2009;Brito, Bazzoli, 2009;Gómez-Ramírez et al, 2011;ObandoBulla et al, 2013). In spite of these efforts, very little is known about the neuroendocrinology of reproduction in cardinal tetra, particularly regarding the neuroanatomical organization of the preoptic-hypothalamus-hypophysis complex.…”

Efecto del pH sobre la proporción oocitaria de Paracheirodon axelrodi, en cautiverio

“…Teniendo en cuenta las guías para el manejo ético de peces para la investigación (AVMA, 2007), se sacrificaron, mensualmente, 10 individuos por tratamiento, escogidos de forma aleatoria. Los ejemplares fueron anestesiados con benzocaína 0.1 g/l y sacrificados por corte medular a nivel cervical (Tovar, et al, 2009;Gómez et al, 2011).…”

“…B a j o e l estereoscopio, se diseccionó a los ejemplares, observando el contenido visceral para identificar la presencia de la gónada a nivel macroscópico. Una vez extraídas las muestras gonadales, se sometieron a un proceso de deshidratación e inclusión en parafina (Tovar, et al, 2009;Gómez, et al, 2011).…”

“…Los cortes fueron teñidos con la técnica de Mayer y Harris hematoxilina-eosina (HyE). Finalmente se realizó el montaje de los cortes en láminas con citorresina (Tovar, et al, 2009;Gómez, et al, 2011).…”